Thermostat.



No. 63|,27a. n Patented Aug. 22, |899. J. BUTCHER.

THERMOSTAT.

lApplicution filed Oct. 22, 1898.)

2 Sheets-Sheet l,

\ x x x x MII No. 631,278. Patented Aug. 22,--1899.

J. BUTCHER. THERMOSTAT.

(Application filed Oct. 22, 1898.

(No Modem 2 Sheets-Sheet 2,

UNITED STATES PATENT OFFICE.

JOSEPH BUTOHER, OF JERSEY CITY, NEV JERSEY.

THERMOSTAT.

SPECIFICATION forming part of Letters Patent No. 631,278, dated August 22, 1899.

.Application filed October 22,1898. Serial No. 694,248. (No model.)

To all whom, t may concern:

Be it known that I, JOSEPH BU'rcHER, a citizen of the United States, residing at Jersey City, Hudson county, New Jersey, have invented certain new and useful Improvements in Thermostats, of which the following is a specification.

This invention relates to the class of thermostats such as those employed in heat-regulating 1n echanisms controlled or operated electrically.

The object of the invention is to provide a simple, inexpensive, and very sensitive thermostat adapted to act positively under very slight changes in temperature.

In the accompanying drawings,which illustrate an embodiment of the invention, Figure l is a face View or front elevation of the. thermostat. Fig. 2 is a similar view, but with the faceplate omitted. Fig. 3 is a View of the back or under side of the thermostat. Fig. 4 is a longitudinal axial section of the thermostat. Figs. 5, 6, and 7 are transverse sections in the respectivey planes indicated by lines 005, mi, and x7 in Fig. l.. Fig. S shows the thermal element detached in perspective. Fig. 9 is a general diagrammatic View on a small scale, illustrating one application of the thermostat to the regulation of the heat of a furnace.

In the general view Fig. 9, T represents the thermostat as a whole; F, a furnace to supply heat 5 M, an electric motor adapted to control the dampers of the furnace F, and .B is a battery which supplies electric energy to the motor M.

This invention has to do with the thermostat T, the purpose of which is to control the operation of the Amotor M.

In the thermostat as illustrated in Figs. l to 7 l is a base-piece, which will be by preference of wood, compressed fiber, or the like. The preferred form of this base-piece is fully illustrated. It is elongated and has a longitudinal recess 2, Fig. 2, in its face to receive the thermal element 3. This element is com- This element o is mounted in the recess 2 ofthe base on the free end of a spring-tongue 4, which will be by preference formed integrally with the basepiece l, said tongue having a little room for lateral play at its free end, on which the thermostatic element .5 is fixed. The free end of the element 3 is situated between two contactscrews 5n and 5b, set in the base-piece and forming terminals of conductors w and a", respectively, leading directly to the motor M, as seen in Fig. 8. On the free end of the tongue et and conveniently formed on the flange-piece 3L of the element 3 is a pin or projection which engages a recess, Fig. 2,

- in a rotatively-mounted post or arbor 7, set

in the base-piece l. By rotating this post to the right or left the tongue at may be deflected a little at its free end to the right or left, thus carrying the fixed end of the member 3 with it and deiiecting the free end of the latterin the opposite direction. n

Mounted on the base-piece l is aface-plate 8, on which is marked a scale or series of graduations s, indicating degrees and curved so as to be concentric to the post 7, and to the latter is fixed a pointer p, which traverses the scale when the post 7 is turned.

New if the post or arbor 7 be turned to the left, say, to SOO on the scale s, as seen in Figs. l and 2, the free end of the member 3 will be moved over into contact with the contactscrew 5, which may be called the cclosingcontact, as it causes the current to llow through the motor M and close the dampers of the furnace F. This operation will cause a rise in temperature, and the zinc strip of the element 3, which has a much greater coefficient of expansion than that of the glass strip g, will expand lengthwise, and it follows that the member 8 will be flexed to such an extent that when the temperature reaches 8OO its extremity will contact with the other contact-screw 5b, which may be called the opening-contact, as this contact closes the circuit through the motor M and causes the latter to open the dampers ofthe furnace F.

Then the free end of the thcrmostatic member 3 is in electrical con tact with either of the contact screws 51L or 5, the current flows from the battery B by a conductor n to a switch-post 9, Figs. 3 and 4, thence through a switch-arm l0 to a post ll, thence bya con- ICO ductor u' to a supporting-post S of the lacetemperature will reach that point before the plate S, thence through said plate to a supporting-post Sb at the other end of said plate anda conductor/t'2 to the zinc .2',thence through said zinc to the contact-screw or 5b, thence to the conductor it' or te to the motor M, and thence from the said motor by a conductor u,

Fig. 9, to the other pole ot' the battery B.V

These posts form, with the cont-act-screws, the terminals of a branched circuit leading tothe motor M.

In the operation of this thermostat the user may place it in any room wherein the temperature is to be regulated, and he may set the pointer p to any degree marked on the scale s. rlhe contact-screws 5"u and screw transversely through metal posts 5C and 5, set in the base-piece, so that the contacts and 5b may be adj usted with greatnicety with reference to the contact-s at the free end of the member 3. As the flexing of the tongue l, which will be still and sprin'gy, requires some little force, a friction-producing device is employed to hold the arbor 7 in position atter it is turned, and this device is best illustrated in Fig. 7. The arbor has at the bottom a journal which occupies a bearing in the base-piece l, a rather thick body in which is formed the recess to engage the projection C on the member 3, an elongated neck which projects up through the face-plate S, and a removable milled head which lits on said neck. The pointer p extends through the lower part of said milled head and the arbor 7 and is held in place iirmlyby a set screw 7, driven down into the top of the arbor 7. Under the faceplate S and bearing upwardly at its ends against the same is a leaf-spring l2, through the center of which the neck of the arbor passes, said spring being seated ona shoulder on the arbor. This spring being compressed between the face-plate and the said shoulder', friction is created, which resists to the proper degree the rotation oi' the arbor and holds it where it is set.

It the operator desires, he may turn the arm of the switch l0 ott' from the post ll, and thus open the circuit, or he may turn it to rest upon either of the posts 5@ and 5d, whereby he may keep the dampers open or closed. For example, if he shifts the arm of the switch to the post 5F the dampers will be held open and it tothe post 5d they will be held closed. rlhe switch l0 is therefore capable ofA performing several functions-namely, to connect the thermostat with a battery and motor, to break the circuit from the battery to the motor, to close a circuit to keep the dampers closed, and to close a circuit to keep the dampers open.

The normal temperature, a change from which causes the thermostat te act, may be taken at any desired degree and the pointer p set to that degree on the scale s, when the tongue et is in its normal position and not under strain or tension. In the drawings the normal is supposed to be and in Figs. l and 2 the pointer is set to 800, so that the dampers are opened.

The current is described as flowing through the wire r2, Fig. 2; but this wire may be considered merely as a precautionary conductor, as the current will Iiow as well from the plate S to the arbor 7 and thence to the zinc through the projection (5. Indeed, it is only necessary that the Zinc .e shall be connected electrically with the post ll, and it is not important to my invent-ion how this connection is made.

Zinc andl glass are employed in forming the thermostatic element for the reason that they are solids capable of being made into strong and rigid strips. They do not corrode, rust, or deteriora-te in use even when employed for an indefinite period. They are very cheap and easily obtainable, and the difference in their coeilicients of expansion is so great as to render the thermostat very sensitive. The contact-screws 5 and b enable the movement of the free end of the zinc e' to be regulated very nicely, the movement allowed corresponding, by preference, to 50 of temperature, although it may be made to work down to lo; but the range of 5 is preferred, as it obviates starting the dampers by the temporary opening of windows or doors when the thermostat is employed to control the dampers of alleating apparatus.

rllhe motor M has not been illustrated herein except diagramma-tically, as it forms no part oi' this invention, and motors ot this general character and capable of being used in connection with the thermostat described are known. It need onlybe said that the motor may comprise an electiomagnet with a vibrating armature which actuates a pawl, this latter imparting rotation to a ratchet-wheel which operates the dampers. lVhen the damper is fully closed, the closing branch of the circuit will be broken at the motor, and when the temperature acts on the thermostat to close the opening branch of the circuit the motor will be set in motion to open the damper. When this opening is effected, the opening branch of the circuit will be broken at the motor.

In the drawings the element 3 is represented as wrapped with wire, but this is not essential at all. ln cementing the Zinc and glass strips together it is convenient to wrap them with a iine wire until the cement hardens or sets, and this wire is not ordinarily removed, although it might be, as the cement, which will be by preference tough and somewhat elastic, will hold the strips irmly together face to face. The zinc strip will project at both ends of the element beyond the strip of glass. rlhe purpose of this is to provide metallic contact at both ends of the element and to avoid the necessity of drilling the glass. The member 3 extends back over the tongue and is out of contact with the latter along its free portion. The engagement of the projec tion e with the recess in the arbor 7 is a coup- IOO IIO

ling or connection substantially similar to a a tooth of a rack engaging between the teeth of a pinion; but the rotatory movement ofthe arbor is so limited that only one tooth and recess are needed.

Having thus described my invention, l claiml, A thermostat having its element 3 composed of a strip of glass g, and a strip of zinc s, secured together face to face, substantially as set forth.

2. A thermostat having its element 3 composed of a strip of glass and a strip of zinc cemented together, face to face, the strip of zinc extending beyond the glass at both ends, substantially as set forth.

A thermostat having a base provided with a springtongue, a thermostatic element secured at one end to the free end of said static element 3, fixed at one end to the free end of said tongue and extending back over the same, electrical contaet-terminals adjacent to the free end of said element, and means for moving the free ends of said tongue i laterally, substantially asset forth.

5. A thermostat having a base-piece provided With a spring-tongue, a thermostatic element secured at one end to the free end of said tongue and extending back over said tongue, electrical terminal contacts on said base adjacent to the free end of said element, a face-plate having a scale s, and mounted on said base-piece, an arbor 7, mounted in the base-piece adjacent to the free end of said tongue and carrying a pointerp adapted to traverse said scale when the arbor is turned, and means coupling said arbor and the free end of said tongue whereby the tongue is moved laterally by the rotation of the arbor7 substantially as set forth.

In Witness whereof I have hereunto signed my name, this 19th day of July, 1398, in the presence of two subscribing Witnesses.

JOSEPH BUTOHER.

Witnesses:

PETER A. Ross, HENRY CoNNnT'r. 

